A mobile communication system was developed in order to provide voice service while securing user mobility. However, the mobile communication system gradually extends service coverage to data service from the voice service and currently reaches a high-speed data service. Currently used mobile communication systems have problems of lack of resources and cannot satisfy user demands for ultra-high-speed service, and thus enhanced mobile communication systems are needed.
The most important one of requirements of a next-generation wireless access system is to support a high data transfer rate. To achieve this, various technologies such as multiple input multiple output (MIMO), cooperative multi-point transmission (CoMP), relay, etc. are developed and studied.
To maximize performances of these technologies, a downlink control channel used in existing systems cannot be employed. Accordingly, 3GPP LTE-A systems introduce an enhanced physical downlink control channel (e-PDCCH) in order to increase the capacity of a PDCCH used in 3GPP LTE systems.
In a wireless access system supporting the e-PDCCH, a base station (BS) needs to set which one of the PDCCH and e-PDCCH is used to transmit downlink control information. Furthermore, an user equipment (UE) needs to set an e-PDCCH region in order to correctly receive the downlink control information.